micro ftir0 lab-intro
TRANSCRIPT
Chemical Microanalysisfor Industry
State-of-the-Art Analysis for hireMedical Device Problem Solving
Polymer Problem SolvingIndustrial Problem Solving
Asbestos Analysesetc., etc., etc.
byJohn Donohue201-294-2581
Hello. I’m John Donohue and this is the best Infrared Microscope ever made byany manufacturer: Nicolet’s IR-Plan Research Microscopemounted on a Magna 560 MainbenchThis amazing instrument allows my Labto obtain the Chemical Identity, via the Infrared Spectrum, of an area as small as 10 microns by 10 microns (10μX10μ). That’s as small as 9 red blood cells placed in a 3X3 square.
When you can chemically identify objects that small you can perform such amazing investigations that theycan often depart completely from the expected and traditional uses of Infrared Spectroscopy, as you will see.
These documents will describe the type of analyses I perform for Industry and Publication using this instrument and the other equipment in my Laboratory.
Part 1: Introduction to the Technology and Method
Mirrored “Lampshade”
Mirrored “Flying Saucer”
Hard Silicon Surface for ATR “Contact” Spectra
My IR-Plan is usually set up with Two Reflachromats:One For Reflection And Transmission, The Other Dedicated To ATR
More “Specialized Reflachromats” and Visible Light Objectives are available, if needed
… and Visible Light Objectives forVisible and Polarized Light Microscopy
Microscope Reflection ModeLightpath
The Upper Reflachromat objective projects a conical surface of IR radiation through the sample. It reflects off the shiny metal beneath the sample and follows the same conical surface up through the sample, back to the objective, and from there to the detector.
This mode is very fast and easy to perform. The shiny metal substrate is usually 0.005 inch aluminum sheet taped onto a microscope slide. It is cut from 5 inch by 5 inch sheet that is cheap and disposable. It can also be performed on any flat or curved metal surface such as injection molding tool surfaces, medical steel cannulas, engine valves, gun metal, you name it.
To Detector
From Source
Sampleon metal
Shiny Metal Substrate
Shiny Metal Substrate
>The FTIR Microscope increases greatly the utility of FTIR and allows the successful use of IR in analyses that simply could not be done by a Mainbench alone.
>The Micro - ATR Objective obtains surface spectra (of the top ~micron of material) with almost no sample prep. This is excellent for thin coatings or surface analysis.
>The FTIR Microscope can obtain useful spectra from extremely thin samples as small as a 10μ X 10μ Square. The amount of mass providing such a signal can approach the Detection Limits of GC/MS
>Example - FTIR Microscope’s Limit of Detection is about a 10μ X 10μ Square : If sample is 1μ thick, 10μ X 10μ X 1μ sample of Polyethylene = how many grams? 1cc of PE = 1g = 10mm X 10mm X 10mm = 1000 cubic mm = 103 mm => 10mm X 10mm X 10mm = 104 μ X 104 μ X 104 μ = 1012 cubic microns => So: 1012 cubic microns = 1g
10μ X 10μ X 1μ =100 cubic microns = 102 cubic microns 102 / 1012 = 10-10 g So: 10μ X 10μ X 1μ sample of Polyethylene = 0.0000000001 grams of PE
So, the FTIR Microscope can ID 100 trillionths of a gram of PE
UNIQUE ADVANTAGES OF THE FTIR MICROSCOPEHow sensitive is it? See arithmetic below.
Microscope ATR Mode LightpathThe ATR Reflachromat objective projects a conical surface of IR radiation onto the inside of the ATR Crystal’s Sample Contact Point. A small part of the IR radiation “tunnels” into the sample touching this Contact Point. Some of it is absorbed and the rest continues on to the detector.
This mode is particularly well-suited to surface analysis (surfaces that are bioactive, drug eluting, bioresorbable, coated, “blooming” additives, lubricious, non-thrombogenic, etc.).
It is also a good choice for highly absorbing materials that are difficult to get an IR beam in and out of such as Black Rubber.
From Source
To Detector
Sample Sample
How Small Can Samples Be?How small IS the 10μ X 10μ Limit of Detection?
Back of USA Penny
LincolnMemorial
Lincoln seated on Penny’s back
This image is 11.2mm X 8.5mm.
Lincoln seated on Penny’s back; mm scale to left
This image is 3.0mm X 2.3mm.
IR-Plan Visible Light 10X Objective view (Glass)Lincoln’s Head and Shoulders
This image is 550μ X 420μ
IR-Plan IR Objective 15X Reflachromat view: Lincoln’s Head
This is the magnification at whichKnife-edge apertures are used to frame
the area to be analyzedand FTIR Spectra are obtained.
10μ X 10μ
This image is 390μ x 300μ
Limit ofDetection:
“Lincoln’s “Eye”
Lincoln’s Face on the previous slide is about 140μ X 120μ.The IR-Plan can obtain good spectra from much smaller samples than this (see asbestos ribbon, below). The thin polymer coating on Lincoln’s Face is easily IDdas Polycarbonate.